1. Field of the Invention
The present invention generally relates to a hybrid vehicle including an engine, an electric generator joined to the engine, and an electric drive motor. Particularly, the present invention relates to the layout of the engine and the electric generator.
2. Description of the Related Art
There has been known a hybrid vehicle including an engine and a drive motor as driving power sources, in which the engine, an electric generator, and the drive motor are arranged in an engine room in a front portion of the hybrid vehicle. Japanese Laid-Open Patent Application Publication No. 2011-73582 discloses a series-hybrid vehicle having a layout in which an engine which has a relatively small size and outputs a low driving power is placed such that its crankshaft extends in a vehicle width direction, the electric generator is joined to one end portion of the engine in the vehicle width direction, and the drive motor for driving front wheels is positioned forward relative to the engine.
However, in the above stated layout in which the electric generator and the engine for actuating the electric generator are arranged in the vehicle width direction, a unit of the engine and the electric generator having a unitary structure increases in length in the vehicle width direction. As a result, it is difficult to flexibly lay out components in a limited space of the engine room. For example, in multi-purpose vehicles such as a golf cart or a farming truck, the engine room is smaller than those of general vehicles. If the unit of the engine and the electric generator which is elongated in the vehicle width direction is incorporated into the hybrid vehicle, it is difficult to lay out an air-intake system of the engine, an exhaust system of the engine, and auxiliary devices, in a space in the vicinity of the unit. If a wasted space increases because of the layout, it may be difficult to dispose in the engine room, an electric power controller for controlling electric power supply to the electric generator, and other components.
A single-cylinder reciprocating engine is commonly used as the relatively small engine. In that case, vibration generated in the engine tends to be problematic. If the engine is placed such that the cylinder extends vertically as described above, reciprocation of a piston causes a vehicle body to vibrate vertically (up and down), which may make a driver feel discomfort. In the multi-purpose vehicle having a relatively simple vehicle body structure, such as a golf cart, it is not easy to suppress the vibration generated in the engine from being transmitted to the vehicle body. As a result, the driver may feel substantial vibration.